Problem: Ishaan ate 3 slices of pie. Christopher ate 4 slices. If Ishaan ate $\dfrac{3}{9}$ of the pie, what fraction of the pie is remaining?
Explanation: If 3 slices represent $\dfrac{3}{9}$ of the pie, there must have been a total of 9 slices. $\text{fraction of pie remaining} = \dfrac{\text{number of slices remaining}}{\text{number of slices total}}$ Together they ate 7 slices, which leaves 2 out of 9 slices remaining. There is $\dfrac{2}{9}$ of the pie remaining.